Bitcoin should be adopted as legal tender worldwide.

People should be allowed to use as currency anything they like, including Bitcoin.

Cryptocurrencies offer significantly more value than fiat currencies due to their greater security, privacy, and portability.

FIAT currencies owned and regulated by banking groups have too much power.

If bitcoin is adopted as a legal tender, all the other cryptocurrencies (ex. ethereum, iotacoin etc...) would make their best to enter the Cryptocurrency masterrace, creating competition, which would improve the economy.

Unlike money which can be printed infinitely and therefore inflate out of control; BTC is finite and progressively harder to create.

Bitcoin really doesn't have a standard value. Unlike FIAT currencies, the value of BTC has fluctuated wildly and violently, so much so that many stores and markets will not accept BTC as a form of payment. The bottom line is that BTC is too volatile to be accepted as legal tender.

It's new, scary and barely understood.

The division in this argument alone serves as a rationale for why bitcoin should not be a global legal tender: because not everyone is willing to accept it. So it's not whether if it should, but whether if it even can.

If everyone adopts it as primary currency, and something goes wrong, it will crash the entire planet's economy.

Bitcoins are produced with too much energy.

This would prevent central control of the monetary system. Lack of monetary policy exposes economies to the unmitigated risk of economic pathologies.